function animate(obj,target,callback){
    clearInterval(obj.timer)
     obj.timer = setInterval(function(){
        // var step = Math.ceil((target - obj.offsetLeft) / 10)
        var step = (target - obj.offsetLeft) / 10
       step = step > 0 ? Math.ceil(step) : Math.floor(step);
        if(obj.offsetLeft==target){
            clearInterval(obj.timer)
            if(callback){
                callback()
            }
        }else{
            obj.style.left=obj.offsetLeft + step +'px'
           
        }
       
    },15)
}
